1. Field of the Invention
The present invention relates to a plating apparatus and a plating method for a substrate, and more particularly to a plating apparatus and a plating method for a substrate for filling a metal such as copper (Cu) or the like in fine interconnection patterns (recesses) formed on a semiconductor substrate.
The present invention also relates to an electrolytic treatment method for applying electrolytic treatment, such as plating or etching, to the surface of a substrate to be treated, and an apparatus therefor.
The present invention further relates to an electrolytic treatment apparatus for applying, for example, plating or etching to the surface of a member to be treated, especially an electrolytic treatment apparatus and a method for controlling the state of its electric field.
2. Description of the Related Art
Aluminum or aluminum alloy has generally been used as a material for forming interconnection circuits on semiconductor substrates. As the integrated density increases, there is a demand for the usage of a material having a higher conductivity as an interconnection material. A method has been proposed to plate a substrate to fill an interconnection pattern formed thereon with copper or its alloy.
There are various processes known including CVD (chemical vapor deposition), sputtering, etc. to fill the interconnection pattern with copper or its alloy. However, if the material of the metal layers is copper or its alloy, i.e., for forming copper interconnects, the CVD process is costly, and the sputtering process fails to embed copper or its alloy in interconnection patterns having a high aspect ratio, i.e., a high ratio of depth to width. The plating process is most effective to deposit a metal layer of copper or its alloy.
Various processes are available for plating semiconductor substrates with copper. They include a process of immersing a substrate in a plating liquid held at all times in a plating tank, referred to as a cup-type or dipping-type process, a process of holding a plating liquid in a plating tank only when a substrate to be plated is supplied to the plating tank, an electrolytic plating process of plating a substrate with a potential difference, and an electroless plating process for plating a substrate with no potential difference.
Conventionally, a plating apparatus for performing this type of copper plating was equipped with a horizontal arrangement of a plurality of units, such as a unit for performing a pretreatment step incidental to plating, a unit for performing a cleaning/drying step after plating, and a unit for performing a plating step, and a transfer robot for transferring the substrate between these units. The substrate was subjected to a predetermined treatment in each unit while being transferred between the units, and was sequentially transported to a subsequent step after plating treatment.
In the conventional plating apparatus, however, separate units were provided for respective steps, such as plating treatment and pretreatment, and the substrate was transferred to the respective units and treated thereby. Thus, there were problems that the apparatus was considerably complicated and difficult to control, occupied a great area, and involved a considerably high manufacturing cost.
With electroplating, moreover, if air bubbles are present in a plating liquid filled between a surface to be plated of a substrate (cathode) and an anode, the air bubbles, as insulators, function as if they were anode masks. As a result, the film thickness of a plating formed at positions corresponding to these portions may decrease, or a complete lack of plating may occur. To obtain a uniform, high quality plated film, therefore, it is necessary to leave no air bubbles in the plating liquid between the surface to be plated of the substrate and the anode.
Furthermore, electrolytic treatment, especially electroplating, is widely used as a method for forming a metal film. In recent years, copper electroplating for multilayer interconnects of copper, and gold electroplating for bump formation, for example, have attracted attention because of their effectiveness (inexpensiveness, hole filling characteristics, etc.), and have found increased use, for instance, in the semiconductor industry.
FIG. 71 shows a conventional general constitution of a plating apparatus for applying electroplating onto the surface of a substrate to be treated (hereinafter referred to as a substrate), such as a semiconductor wafer, by the use of a so-called face-down method. This plating apparatus includes a cylindrical plating tank 602 opening upward and holding a plating liquid 600 therein and a substrate holder 604 for detachably holding a substrate W face-down and at such a position that the substrate W covers the top opening of the plating tank 602. Inside the plating tank 602, a flat sheet type anode plate 606, immersed in the plating liquid 600 to constitute an anodic electrode, is placed horizontally. On the other hand, a conductive layer S is formed on the lower surface (plating surface) of the substrate W, and this conductive layer S has, at its peripheral edge portion, contact with cathodic electrodes.
A plating liquid jet pipe 608 for forming an upwardly directed jet of the plating liquid is connected to the center of the bottom of the plating tank 602, and a plating liquid receiver 610 is placed on an upper external portion of the plating tank 602.
With the above structure, the substrate W held by the substrate holder 604 is placed face-down above the plating tank 602. The plating liquid 600 is gushed upward from the bottom of the plating tank 602 to strike a jet of the plating liquid 600 on the lower surface (plating surface) of the substrate W. Simultaneously, a predetermined voltage is applied between the anode plate 606 (anodic electrode) and the conductive layer S (cathodic electrode) of the substrate W from a plating power source 612 to form a plated film on the lower surface of the substrate W. At this time, the plating liquid 600 which has overflowed the plating tank 602 is collected from the plating liquid receiver 610.
Wafers and liquid crystal substrates for LSI""s tend to increase in area year by year. In line with this tendency, variations in the film thickness of a plated film formed on the surface of the substrate are posing problems. In detail, to supply a cathode potential to the substrate, contacts with the electrode are provided in a peripheral edge portion of the conductive layer formed beforehand on the substrate. As the area of the substrate increases, the electric resistance of the conductive layer ranging from the contact on the periphery of the substrate to the center of the substrate also increases. As a result, a potential difference is produced in the surface of the substrate, causing a difference in the plating speed, thereby leading to variations in the film thickness of the resulting plated film.
That is, to apply electroplating onto the surface of the substrate to be treated, a common practice is to form a conductive layer on the surface of the substrate to be treated (hereinafter referred to simply as xe2x80x9csubstratexe2x80x9d), bring contacts for supplying a cathode potential into contact with a site on the conductive layer in proximity to the outer periphery of the substrate W, install an anode at a position facing the substrate W, fill a plating liquid between the anode and the substrate W, and apply an electric current between the anode and the contacts with a direct current power source to perform plating on the conductive layer of the substrate W. In the case of a large-area substrate, however, the electric resistance of the conductive layer ranging from the contact close to the outer periphery of the substrate to the center of the substrate W becomes so high that a potential difference arises in the surface of the substrate W, causing differences in the plating speed among respective portions.
FIG. 72 is a view showing the film thickness distribution of copper plated films over the surface of the substrate when copper electroplating was performed, using a conventional general plating apparatus as shown in FIG. 71, on a silicon substrate of 200 mm in diameter having a conductive layer (a copper thin film) with a film thickness of 30 nm, 80 nm and 150 nm formed thereon. FIG. 73 is a view showing the film thickness distribution of copper plated films over the surface of the substrate when copper electroplating was similarly performed on each of silicon substrates of 100 mm, 200 mm and 300 mm in diameter having a conductive layer (a copper thin film) with a film thickness of 100 nm formed thereon. As shown in FIGS. 72 and 73, when the conductive layer is thin, or the diameter of the substrate is large, there are great variations in the distribution of the film thickness of the copper plated film formed by electroplating. In extreme cases, no copper film may be formed in the vicinity of the center of the substrate.
This phenomenon will be explained electrochemically as follows:
FIG. 74 shows an electrical equivalent circuit diagram of the conventional general electroplating apparatus shown in FIG. 71. When a predetermined voltage is applied by a plating power source 612 between the anode plate 606 (anodic electrode) submerged in the plating liquid 600 and the conductive layer S (cathodic electrode) of the substrate W to form a plated film on the surface of the conductive layer S, the following resistance components exist in this circuit:
R1: Power source wire resistance between power source and anode, and various contact resistances
R2: Polarization resistance at anode
R3: Plating liquid resistance
R4: Polarization resistance at cathode (plated surface)
R5: Resistance of conductive layer
R6: Power source wire resistance between cathode potential lead-in contact and power source, and various contact resistances.
As shown in FIG. 74, when the resistance R5 of the conductive layer S becomes higher than the other electric resistances R1 to R4 and R6, the potential difference produced between both ends of this resistance R5 of the conductive layer S increases, and accordingly, a difference occurs in the plating current. Thus, the plated film growth rate lowers at a position distant from the cathode lead-in contact. If the film thickness of the conductive layer S is small, the resistance R5 further increases, and this phenomenon appears conspicuously. Furthermore, this fact means that the current density differs over the surface of the substrate, and the characteristics of plating themselves (resistivity, purity, filling characteristics, etc. of the plated film) are not uniform over the surface of the substrate.
Even in electrolytic etching, in which the substrate is an anode, the same problems occur, merely with the direction of electric current being reversed. In a manufacturing process for a large-diameter wafer, for example, the etching rate at the center of the wafer slows compared with the peripheral edge portion.
As a method for avoiding these problems, it is conceivable to increase the thickness of the conductive layer or decrease the electric conductivity. However, the substrate is subject to various restrictions, even in manufacturing steps other than plating. Furthermore, for example, when a thick conductive layer is formed on a fine pattern by sputtering, voids easily form inside the pattern. Thus, it is impossible to easily increase the thickness of the conductive layer or change the film type of the conductive layer.
Placement of the cathode potential lead-in contacts on the entire surface of the substrate makes it possible to make the potential difference over the surface of the substrate small. However, this placement is unrealistic because the site used as the electrical contacts cannot be used as LSI. Furthermore, increasing the resistance value of the plating liquid (resistance R3, R2 or R4 in FIG. 74) is also effective. However, changing the electrolyte of the plating liquid means changing all of the plating characteristics. Lowering the concentration of metal ions to be plated, for example, brings about the restriction that the plating speed cannot be made sufficiently high.
As described above, in the step of performing electroplating by providing contacts in a peripheral portion of the substrate and using the conductive layer on the surface of the substrate, the problem arises that as the size of the substrate increases, the plated film thickness greatly varies over the surface of the substrate. This problem, in particular, is a major restriction in the semiconductor industry, which places emphasis on the uniformity of the film thickness over the surface of the substrate to be treated, and the uniformity of the process.
The present invention has been accomplished in view of the above-described facts. An object of the present invention is to provide a plating apparatus and a plating method capable of performing plating treatment and treatments incidental thereto with a single unit, and further a plating apparatus and a plating method for a substrate which leave no air bubbles in a plating liquid filled between a surface to be plated of the substrate and an anode.
Another object of the present invention is to provide an electrolytic treatment apparatus and method capable of performing uniform electrolytic treatment over a surface of a substrate, without changing the thickness and film type of a conductive layer, or an electrolyte of a plating liquid or the like.
Still another object of the present invention is to provide an electrolytic treatment apparatus capable of actively controlling an electric field state to achieve the desired distribution of the film thickness over the surface of the substrate, and an electric field state control method for the apparatus.
According to a first aspect of the invention, there is provided a plating apparatus for a substrate comprising a substrate holding portion for holding the substrate such that a surface to be plated faces upward. A cathode electrode causes current to flow by being in contact with the substrate. An anode is positioned above the surface to be plated and a plating liquid pouring means pours a plating liquid into a space between the surface to be plated of the substrate held by the substrate holding portion and the anode brought close to the surface to be plated.
According to this feature, plating treatment is performed with the substrate being held face-up by the substrate holding portion and the plating liquid being filled between the surface to be plated and the anode of an electrode arm portion. After plating treatment, the plating liquid is withdrawn from between the plated surface and the anode of the electrode arm portion, and the electrode arm portion is raised to uncover the plated surface. Thus, pretreatment associated with plating, and other treatments, such as cleaning/drying treatment, can be performed before and after plating treatment, with the substrate being held by the substrate holding portion.
According to a second aspect of the invention, the plating apparatus according to the first aspect has a plating liquid impregnated material composed of a water retaining material is contacted with and held on a lower surface of the anode. In copper plating, it is common practice to use copper, which contains phosphorus with a content of 0.03 to 0.05% (phosphorus-containing copper), as an anode in order to suppress the formation of slime. When phosphorus-containing copper is used as the anode, what is called a black film is formed on the surface of the anode as plating proceeds. In such a case, the plating liquid impregnated material is holding the plating liquid therein to wet the surface of the anode, thereby preventing fall of the black film onto the plated surface of the substrate, and simultaneously facilitating extraction of air to the outside when the plating liquid is poured between the surface to be plated and the anode.
According to a third aspect of the invention, the plating apparatus according to the first aspect comprises a cathode portion and a plating liquid tray disposed laterally of the cathode portion. The anode is movable between the cathode portion and the plating liquid tray. According to this feature, the anode is immersed in the plating liquid in the plating liquid tray and wetted thereby when plating treatment is not performed. Thus, drying and oxidation of the black film formed on the anode surface can be prevented.
According to a fourth aspect of the invention, the plating apparatus according to the first aspect comprises a cathode portion and a plurality of nozzles disposed laterally of the cathode portion. The nozzles jet a pretreatment liquid, a cleaning liquid, a gas or the like toward the surface to be plated held by the substrate holding portion. According to this feature, the pretreatment liquid or the cleaning liquid is jetted from the nozzles toward the surface to be plated in a state in which the substrate, before and after plating treatment, is held by the substrate holding portion and its surface to be plated is uncovered facing upwards. Hence pretreatment and cleaning treatment can be performed.
According to a fifth aspect of the invention, the plating apparatus according to the first aspect comprises a cathode portion wherein the substrate holding portion is capable of ascending and descending between a lower substrate transfer position, an upper plating position where a peripheral edge portion of the surface to be plated contacts the cathode portion, and a pretreatment/cleaning position intermediate these positions. As described above, the substrate holding portion is raised and lowered so as to correspond to respective operating positions. Thus, greater compactness and improved operating properties are achieved.
According to a sixth aspect of the invention, a plating method for a substrate comprises sealing a peripheral edge portion of a surface to be plated in a watertight manner. The surface to be plated faces upward and is electrically connected to a cathode electrode. An anode is positioned closely above the surface to be plated and pouring a plating liquid is poured into a sealed space between the surface to be plated and the anode.
According to a seventh aspect of the invention, remaining plating liquid is removed by a plating liquid recovering nozzle after plating according to the sixth aspect.
According to an eighth aspect of the invention, the plating method according to the sixth aspect comprises moving a pre-coating/recovering arm to a position facing the substrate before plating and supplying a pre-coating liquid from a pre-coating nozzle to perform pre-coating treatment.
According to a ninth aspect of the invention, the plating method according to the sixth aspect comprises positioning a plating liquid impregnated material composed of a water retaining material in a space between the surface to be plated and the anode and holding the plating liquid inside the plating liquid impregnated material.
According to a tenth aspect of the invention, there is provided a plating apparatus for a substrate comprising an anode positioned above a surface of the substrate to be plated held by a substrate holding portion and a cathode electrode for causing current to flow by being in contact with the substrate. A plating liquid impregnated material composed of a water retaining material is positioned in a space between the surface to be plated and the anode to perform plating.
According to an eleventh aspect of the invention, the plating apparatus according to the tenth aspect has the plating liquid impregnated material be a high resistance structure.
According to a twelfth aspect of the invention, the plating apparatus according to the tenth aspect has the plating liquid impregnated material comprising a ceramic.
According to a thirteenth aspect of the invention, a plating apparatus for a substrate, plates a surface to be plated such that the plating liquid impregnated material is out of contact with the surface to be plated. A plating liquid is filled into a gap between the plating liquid impregnated material and the surface of the substrate to be plated.
According to a fourteenth aspect of the invention, a plating apparatus performs plating treatment and cleaning/drying treatment in a single unit by raising and lowering the substrate so as to correspond to respective operating positions, with the substrate being held by a substrate holding portion.
According to a fifteenth aspect of the invention, a plating apparatus according to the fourteenth aspect comprises an anode positioned above the surface of the substrate to be plated and a cathode electrode for causing current to flow by being in contact with the substrate. A plating liquid impregnated material composed of a water retaining material is positioned in a space between the surface to be plated and the anode.
According to a sixteenth aspect of the invention, a plating method for a substrate comprises transferring the substrate into a plating unit with a transfer robot after withdrawing the substrate from a loading/unloading unit housing the substrate, holding the substrate with a substrate holding portion in the plating unit, and performing treatments in a single unit by raising and lowering the substrate so as to correspond to respective operating positions for performing plating treatment and cleaning/drying treatment with the substrate being held by the substrate holding portion.
According to a seventeenth aspect of the invention, a plating apparatus for a substrate comprises a loading/unloading unit housing the substrate, a plating unit for performing plating treatment and treatment incidental thereto in a single unit, and a transfer robot for transferring the substrate between the loading/unloading unit and the plating unit.
According to an eighteenth aspect of the invention, a plating apparatus for a substrate comprises an anode positioned above a surface of the substrate held by a substrate holding portion, a cathode electrode for causing current to flow by being in contact with the substrate, and a pure water supply nozzle. The substrate and the cathode electrode are simultaneously cleaned by supplying pure water from the nozzle after completion of plating.
According to a nineteenth aspect of the invention, a plating apparatus for a substrate comprises a substrate holding portion for holding the substrate, a cathode electrode for causing current to flow by being in contact with the substrate held by the substrate holding portion, an anode positioned closely to the substrate, and plating liquid pouring means for pouring a plating liquid into a space between the surface to be plated and the anode. The plating liquid pouring means is constituted such that the plating liquid is poured between the anode and the surface to be plated from a plating liquid pouring path provided in part of the anode or provided around an outer peripheral portion of the anode and is spread on the surface of the substrate to be plated.
According to a twentieth aspect of the invention, the plating apparatus according to the nineteenth aspect comprises the substrate holding portion for holding the substrate such that the surface to be placed faces upward, a seal material for holding the plating liquid on the surface to be plated, the cathode portion having a cathode electrode for causing current to flow by being in contact with the substrate, an electrode arm portion having the anode movable horizontally and vertically in proximity to the cathode electrode, and plating liquid pouring means for pouring a plating liquid into a space between the surface to be plated and the anode. The plating liquid pouring means is constituted such that the plating liquid is poured between the anode and the surface to be plated from a plating liquid pouring hole provided through part of the anode or a nozzle provided around the outer peripheral portion of the anode and is spread on the surface to be plated.
According to this features, plating treatment is performed with the substrate being held face-up by the substrate holding portion and the plating liquid being filled between the surface to be plated and the anode of the electrode arm portion. After plating treatment, the plating liquid is withdrawn from between the plated surface and the anode of the electrode arm portion, and the electrode arm portion is raised to uncover the plated surface. Thus, pretreatment associated with plating, and other treatments, such as cleaning/drying treatment, can be performed before and after plating treatment, with the substrate being held by the substrate holding portion. Furthermore, when the plating liquid is poured between the surface to be plated and the anode, flow of the plating liquid spreading all over the surface to be plated occurs. Along with this flow of the plating liquid, air between the surface to be plated and the anode is pushed outward so that enclosure of air by the plating liquid is prevented. Consequently, air bubbles are prevented from remaining in the plating liquid filled between the surface to be plated and the anode.
According to a twenty-first aspect of the invention, the plating apparatus according to the twentieth aspect has the plating liquid pouring means having a plating liquid introduction path provided along a diametrical direction of the anode on a surface of the anode opposite to a surface of the anode facing the substrate, and connected to a plating liquid supply pipe. The plating liquid pouring hole is provided at a position facing a plating liquid introduction hole provided so as to open toward a surface of the plating liquid introduction path located at the anode side. According to this feature, a plating flow occurs in a direction perpendicular to the plating liquid introduction pipe, in accordance with the pouring of the plating liquid between the surface to be plated and the anode.
According to a twenty-second aspect of the invention, the plating apparatus according to the nineteenth aspect has the plating liquid pouring means having a plating liquid introduction path which is provided in a cruciform, radial or circumferential form on a surface of the anode opposite to a surface of the anode facing the substrate, and is connected to a plating liquid supply pipe. The plating liquid pouring hole is provided at a position facing a plating liquid introduction hole provided so as to open toward a surface of the plating liquid introduction path located at the anode side. According to this feature, a plating flow which spreads radially in respective quadrants partitioned by the plating liquid introduction pipe occurs in accordance with the pouring of the plating liquid between the surface to be plated and the anode.
According to a twenty-third aspect of the invention, a plating method for a substrate comprises positioning an anode closely to at least part of a surface of the substrate to be plated which is electrically connected to a cathode electrode and pouring a plating liquid between the surface to be plated and the anode. A plating liquid column which bridges the surface to be plated and the anode is formed and the plating liquid is poured with the plating liquid column as a starting point.
According to a twenty-fourth aspect of the invention, the plating method according to the twenty-third aspect has the plating liquid poured between the surface to be plated and the anode from a plating liquid pouring path provided in part of the anode or provided around an outer peripheral portion of the anode.
According to a twenty-fifth aspect of the invention, there is provided a plating method for a substrate comprising positioning an anode closely to at least part of a surface of the substrate to be plated which is electrically connected to a cathode electrode and filling a plating liquid into a space between the surface to be plated and the anode by covering the plating liquid on the surface to be plated and bringing the substrate and the anode close to each other gradually under relative rotation. According to this feature, air bubbles between the substrate and the anode can be gradually moved outward and driven off as the substrate and the anode approach each other.
According to a twenty-sixth aspect of the invention, the plating method according to the twenty-fifth aspect has a plating liquid impregnated material composed of a porous substrate having water retaining properties placed on a surface of the anode facing the substrate and means for spreading the plating liquid between the plating liquid impregnated material and the substrate radially outwardly by relative rotation of the plating liquid impregnated material. The substrate is provided on a surface of the plating liquid impregnated material facing the substrate. According to this feature, air bubbles between the substrate and the anode can be driven off nearly completely.
According to a twenty-seventh aspect of the invention, there is provided an electrolytic treatment method in which a high resistance structure is provided in at least part of an electrolytic solution filled between a substrate to be treated having contact with one electrode of an anode and a cathode and the other electrode facing the substrate to be treated to perform electrolytic treatment of the surface of the substrate to be treated. The high resistance structure has an electrical conductivity lower than that of the electrolytic solution.
According to this feature, the electric resistance between the anode and the cathode submerged in the electrolytic solution is made higher via the high resistance structure than the electric resistance in the presence of the electrolytic solution only, so that the difference in current density over the surface of the substrate to be treated due to electric resistance can be decreased. In this case, electroplating can be performed by bringing the substrate to be treated into contact with the contact of the cathode, or electrolytic etching can be performed by bringing the substrate to be treated into contact with the contact of the anode.
According to a twenty-eighth aspect of the invention, the electrolytic treatment method according the twenty-seventh aspect has the high resistance structure constituted such that a resistance thereof in an equivalent circuit is higher than a resistance in the equivalent circuit between the contact with the electrode on a conductive layer formed on the surface of the substrate to be treated and a portion electrically farthest from the contact. According to this feature, the difference of current density over the surface due to electric resistance of a conductive layer formed on the substrate to be treated can be made even smaller.
According to a twenty-ninth aspect of the invention, the electrolytic treatment method according to the twenty-seventh aspect has the electrolytic treatment performed such that the substrate is held face-up by a substrate holding portion.
According to a thirtieth aspect of the invention, there is provided an electrolytic treatment apparatus for performing electrolytic treatment of a substrate to be treated by filling an electrolytic solution between the substrate, having contact with one electrode of an anode and a cathode, and the other electrode facing the substrate to be treated. A high resistance structure having an electrical conductivity lower than that of the electrolytic solution is provided in at least part of the electrolytic solution.
According to a thirty-first aspect of the invention, the electrolytic treatment apparatus according to the thirtieth aspect has the electrolytic treatment performed such that the substrate is held face-up by a substrate holding portion.
According to a thirty-second aspect of the invention, the electrolytic treatment apparatus according to the thirtieth aspect has the high resistance structure constituted such that a resistance thereof in an equivalent circuit is higher than a resistance in the equivalent circuit between the contact with the electrode on a conductive layer formed on the surface of the substrate to be treated and a portion electrically farthest from the contact.
According to a thirty-third aspect of the invention, the electrolytic treatment apparatus according to the thirtieth aspect has the high resistance structure comprising a porous substance holding an electrolytic solution therein. According to this feature, the electrical resistance of the high resistance structure can be increased via the electrolytic solution, which is complicatedly admitted into the porous substance, and follows a considerably long path, effectively in the thickness direction, even though the structure is a thin structure.
According to a thirty-fourth aspect of the invention, the electrolytic treatment apparatus according to the thirty-third aspect has the porous substance comprising a porous ceramic. As the ceramic, alumina, SiC, mullite, zirconia, titania, cordierite, etc. can be cited as examples. To hold the plating liquid stably, moreover, it is preferably a hydrophilic material. With the alumina-based ceramic, for example, that with a pore diameter of 10 to 300 xcexcm, a porosity of 20 to 60%, and a thickness of about 0.2 to 200 mm, preferably about 2 to 50 mm, is used.
According to a thirty-fifth aspect of the invention, the electrolytic treatment apparatus according to the thirtieth aspect has the high resistance structure provided so as to divide the electrolytic solution into a plurality of parts. According to this feature, it is possible to use a plurality of electrolytic solutions, or prevent contamination or reaction of one of the electrodes from exerting an influence on the other electrode.
According to a thirty-sixth aspect of the invention, there is provided a method for controlling an electric field state in an electrolytic treatment apparatus comprising providing a high resistance structure in at least part of an electrolytic solution filled between a substrate to be treated having contact with one electrodes of an anode and a cathode, with the other electrode facing the substrate to be treated. The high resistance structure has an electrical conductivity lower than that of the electrolytic solution. An electric field of a surface of the substrate to be treated is controlled by adjusting at least one of an exterior shape of the high resistance structure, an internal structure of the high resistance structure, and an attachment of a member having a different electrical conductivity.
If the state of the electric field on the surface to be treated is thus actively controlled to achieve a desired state, the electrolytic treatment of the substrate can be have a desired distribution over the surface. In case electrolytic treatment is plating treatment, the thickness of a plated film formed on the substrate to be treated can be made uniformize, or an arbitrary distribution can be imparted to the thickness of the plated film formed on the substrate to be treated.
According to a thirty-seventh aspect of the invention, the method according to the thirty-sixth aspect has the adjusting of the exterior shape be at least one of adjustment of a thickness of the high resistance structure and adjustment of a shape on a plane of the high resistance structure.
According to a thirty-eighth aspect of the invention, the method according to the thirty-sixth aspect has the high resistance structure comprise a porous substance. The adjusting of the internal structure of the porous substance is at least one of adjustment of a pore diameter distribution thereof, adjustment of a porosity distribution thereof, adjustment of a flexing rate distribution thereof, and adjustment of a combination of materials.
According to a thirty-ninth aspect of the invention, the method according to the thirty-sixth aspect has the adjusting of attachment of the member having the different electrical conductivity be adjustment of a shielding area of the high resistance structure by means of the member having the different electrical conductivity.
According to a fortieth aspect of the invention, there is provided an electrolytic treatment apparatus for performing electrolytic treatment of a substrate to be treated by filling an electrolytic solution between the substrate, having contact with one electrode of an anode and a cathode, and the other electrode facing the substrate to be treated. A high resistance structure, having an electrical conductivity lower than that of the electrolytic solution, is provided in at least part of the electrolytic solution. An electric field of a surface of the substrate to be treated is controlled by adjusting at least one of an exterior shape of the high resistance structure, an internal structure of the high resistance structure, and attachment of a member having a different electrical conductivity.
According to a forty-first aspect of the invention, the electrolytic treatment apparatus according to the fortieth aspect has the adjusting of the exterior shape be at least one of adjustment of a thickness of the high resistance structure and adjustment of a shape on a plane of the high resistance structure.
According to a forty-second aspect of the invention, the electrolytic treatment apparatus according to the fortieth aspect has the high resistance structure comprise a porous substance. The adjusting of the internal structure of the porous substance is at least one of adjustment of a pore diameter distribution thereof, adjustment of a porosity distribution thereof, adjustment of a flexing rate distribution thereof, and adjustment of a combination of materials.
According to a forty-third aspect of the invention, the electrolytic treatment apparatus according to the fortieth aspect has the adjusting of attachment of the member having the different electrical conductivity be adjustment of a shielding area of the high resistance structure by means of the member having different electrical conductivity.
According to a fourth aspect of the invention, there is provided an electrolytic treatment apparatus for performing electrolytic treatment of a substrate to be treated by filling an electrolytic solution between the substrate having contact with one electrode of an anode and a cathode, and the other electrode facing the substrate to be treated. A high resistance structure, having an electrical conductivity lower than that of the electrolytic solution, is provided in at least part of the electrolytic solution. An outer periphery of the high resistance structure is held by a holding member. A seal member is provided between the high resistance structure and the holding member for preventing the electrolytic solution from leaking therethrough and preventing an electric current from flowing.
The high resistance structure may comprise alumina porous ceramics or silicon carbide ceramics. Moreover, the high resistance structure may be constituted by a material formed by bundling vinyl chloride in a fibrous form, and fusing the fibers together, or a material formed by shaping a foam such as polyvinyl alcohol, or a fiber such as Teflon (trade name) into a form such as a woven fabric or a nonwoven fabric. Furthermore, a composite of any of them may be used combined with a conductor and an insulator, or conductors. The high resistance structure may also be composed of a structure having another type of electrolytic solution sandwiched between two diaphragms.
According to a forty-fifth aspect of the invention, there is provided an electrolytic treatment apparatus for performing electrolytic treatment of a substrate to be treated by filling an electrolytic solution between the substrate which has contact with one electrode of an anode and a cathode, and the other electrode facing the substrate to be treated. An electrolytic solution impregnated material is disposed between the other electrode and the substrate to be treated. An electrolytic solution passing hole is provided in the other electrode for supplying the electrolytic solution into the electrolytic solution impregnated material. A pipe is inserted into the electrolytic solution passing hole, and the electrolytic solution supplied into the electrolytic solution impregnated material through the pipe is supplied from an opposite surface of the electrolytic solution impregnated material and filled between the electrolytic solution impregnated material and the substrate to be treated.
As the pipe, it is desirable to select a material which is not attacked by the electrolytic solution. Thus, even when the electrolytic treatment step is repeated by this electrolytic treatment apparatus, the inner diameter of the front end of the pipe does not increase with the passage of time. Hence, the ideal liquid filling state at the initial stage of production is similarly retained with the passage of time. Consequently, the situation where air is engulfed and air bubbles accumulate between the electrolytic solution impregnated material and the substrate to be treated can be avoided, and desired electrolytic treatment is always obtained.
According to a the forty-sixth aspect of the invention, the electrolytic treatment apparatus according to the forty-fifth has an electrolytic solution passage portion provided in the electrolytic solution impregnated material so as to continue to the electrolytic solution passing hole.
According to a forty-seventh aspect of the invention, there is provided an electrolytic treatment apparatus for performing electrolytic treatment of a substrate to be treated by filling an electrolytic solution between the substrate having contact with one electrode of an anode and a cathode, and the other electrode facing the substrate to be treated. An electrolytic solution impregnated material is disposed between the other electrode and the substrate to be treated. An electrolytic solution passage portion, having a predetermined depth, is formed in the electrolytic solution impregnated material. The electrolytic solution supplied from the other electrode side into the electrolytic solution impregnated material through the electrolytic solution passage portion is supplied from an opposite surface of the electrolytic solution impregnated material and filled between the electrolytic solution impregnated material and the substrate to be treated. Even when the electrolytic treatment step is repeated, the inner diameter of the front end of the electrolytic solution passage portion does not increase with the passage of time. Hence, the ideal liquid filling state at the initial stage of production is similarly retained with the passage of time. Consequently, the situation where air is engulfed and air bubbles accumulate between the electrolytic solution impregnated material and the substrate to be treated can be avoided, and desired electrolytic treatment is always obtained.
According to a forty-eighth aspect of the invention, the electrolytic treatment apparatus according to the forty-seventh aspect has a liquid reservoir for storing the electrolytic solution provided between the other electrode and the electrolytic solution impregnated material. The electrolytic solution stored in the liquid reservoir is supplied into the electrolytic solution impregnated material.
According to a forty-ninth aspect of the invention, there is provided an electrolytic treatment apparatus for performing electrolytic treatment of a substrate to be treated by filling an electrolytic solution between the substrate, having contact with one of electrode of an anode and a cathode, and the other electrode facing the substrate to be treated. An electrolytic solution impregnated material is disposed between the other electrode and the substrate to be treated. The electrolytic solution impregnated material is constituted such that a passage resistance of the electrolytic solution passing through the electrolytic solution impregnated material differs according to a location of the electrolytic solution impregnated material. The electrolytic solution supplied from the other electrode side into the electrolytic solution impregnated material is supplied from an opposite surface of the electrolytic solution impregnated material in a supply amount suited for the location, and filled between the electrolytic solution impregnated material and the substrate to be treated.